The present invention relates to a novel ink-jet recording film or, more particularly, to a recording film suitable for recording of information by using an ink-jet printer and capable of rapidly fixing or drying the inked pattern so as to be freed from troubles of re-transfer and smearing or blur even if the inked pattern is rubbed with a finger tip or the inked pattern is overwritten by second ink-jet printing immediately after the first printing.
Along with the rapid progress in the computer technology, it is widely practiced in recent years that computer-processed information of various natures of data and images is processed very conveniently and rapidly into presentation forms such as handout copies and posters by printing out using a suitable printer machine. Various types of printer machines are known and respectively employed in this application including dot-impact printers, laser printers, thermal printers and ink-jet printers, of which ink-jet printers or ink-jet plotters are most widely employed by virtue of the advantages that the machine noise in printing is low, these machines are adaptable to full-color printing and the cost for running the machine is relatively low as compared with other types of printing machines.
Needless to say, the output of an ink-jet printer or plotter is printed on a recording film which basically can be a sheet of plain paper or coated paper. With an object to improve the quality of ink-jet recorded pattern, specific recording films are also used for ink-jet printing as prepared by providing the surface of a base film of a plastic resin with an ink-receptive layer. Such a recording film is sometimes used in the preparation of posters with a colored image because the ink-jet printed material thereon has excellent glossiness.
Several types of ink-receptive layers are proposed in the prior art including a monolayer formed of a blend of two hydrophilic polymers including, one, a polyvinyl alcohol, referred to as PVA hereinafter, and, the other, a polyvinyl pyrrolidone, referred to as PVP hereinafter, disclosed in Japanese Patent Publication 6-427 and a dual layer consisting of an underlayer of a PVP and an overlayer of a PVA as disclosed in Japanese Patent Kokai 7-40646. Since the ink-receptive layer in these recording films is formed from hydrophilic or water-soluble resins, it is unavoidable that, when printing is made on the recording film with a water-base printing ink, the ink-receptive layer absorbs the ink to cause swelling or partial dissolution of the ink-receptive layer so that a length of time is taken before drying of the printing ink absorbed in the ink-receptive layer to accomplish fixing of the printed pattern.
With an object to overcome the above mentioned disadvantages, various attempts and proposals are made in the prior art. For example, Japanese Patent Kokai 7-186521 proposes that an overcoating layer consisting of a blend of a hydrophilic resin and inorganic fine particles of 10 to 300 nm particle diameter is formed on an ink-receptive layer of a hydrophilic resin. Japanese Patent Kokai 7-96655 proposes that an ink-permeable overcoating layer of a hydrophilic resin is formed on an ink-receptive layer containing fine particles of a hydrophobic resin having a particle diameter not exceeding 0.3 .mu.m dispersed in the matrix of a water-absorbing polymer. Further, Japanese Patent Kokai 9-123593 teaches that the ink-receptive layer is formed from a porous underlayer of hydrated alumina and an overcoating layer of a water-soluble resin.
A problem in the above mentioned first and third proposals is that, due to the difficulty in obtaining uniform dispersion of fine particles of an inorganic material or an organic resin in the matrix layer of a hydrophilic or water-soluble resin, the coating workability with the coating composition cannot be high enough consequently with low productivity of the manufacturing process of recording films. The recording film according to the second proposal also has a defect of blocking of the recording films after printing due to the extremely small surface roughness of the ink-permeating layer.